The field of the invention relates to biological disk replacement, Bone Morphogenic Protein (BMP) carriers, and anti-adhesion materials principally for human and animal use.
Attempts at designing an artificial lumbar disk or for that matter any artificial disk have been undertaken for decades. The potential benefit for success is evidenced by total hip and knee replacement surgery which is remarkably successful and has restored mobility for hundreds of thousands who would otherwise be crippled and in constant pain. The technology in spine surgery lags behind, where still the indicted procedure for a deteriorated joint is a fusion. A fusion is not ideal as it obliterates the joint and transfers stress to adjacent joints which in some cases may not be very healthy either. In some patients multilevel degeneration prohibits a good result from spinal fusion. Spinal fusion typically take six to twelve months to complete bony healing and currently there is still a frequent occurrence of these fusions incompletely healing and compromising the result.
A device that allows deteriorated tissue to be replaced by a construct that restores stability and function of the intervertebral disk would quickly replace the fusion procedure and might even be indicated in discectomy cases for herniated disks where there is also joint deterioration. There is currently about 400,000 back operations performed a year in the United States. The majority of such operations are disk procedures and about 20% are fusions.
Currently several disk replacement prototypes have been available or are in development. These range from hydrogel bags to complex ball bearing constructs. So far, no long term satisfactory results have been achieved in humans. Hydrogel bags look most promising, but they have only very short follow-up to date.
Examples of such disk replacement devices can be found in U.S. Pat. No. 4,772,287 (Ray), Waldemar Link prosthesis which has been in use in Europe for nine years, Depuy devices, Motech devices, Acromed devices, Sofamor Danek""s line of artificial disks including Kostuik""s xe2x80x9cSpring Discxe2x80x9d, a ball and socket type with two endplates, Hedrocel spacer, Howmedica hydrogel-based nucleus replacement, and Aesculup/JBS xe2x80x9cprodiscxe2x80x9d of cobalt chrome and polyethylene.
The current design requires that they be placed posteriorly (from the back) which requires significantly hazardous surgery. A disk replacement that could be delivered endoscopically and that was completely biocompatible is ideal.
The normal intervertebral disk consists of a highly hydrophilic (soaks up water) mucopolysccharide central nucleus and a tough fibrocartiliginous outer ring forming a disk-like shape in between each two vertebra. It is an amazingly efficient shock absorber, transferring compressive loads on its center to tensile (stretch) loads on its outer wall. It is analogous to a golf ball with its multilayered rubber band outer portion and a contained liquid center. With age the center chemical substance of the human disk deteriorates and losses its ability to soak up and hold onto water. This results in the nucleus gradually changing from its original gelatinous nature to one similar to crab meat. The outer wall deteriorates also and hence the beginning of the deterioration of the disk which results in symptoms in 80% of the population.
Additionally in conjunction with the replacement of disk and in other types of surgery there can be a need to induce bone growth. This is observed with vertebral type fusion devices which can be packed with bone and/or other materials which may be mixed with bone growth inducing substances.
Further with respect to surgeries directed to disk replacement and other types of surgery scaring may be a problem. Accordingly there is a need to provide anti-adhesion materials to be used in conjunction with surgeries in order to prevent adhesions.
The invention discloses novel biological disk replacement, BMP carriers, and anti-adhesion materials.